mx2.as2.ciberserver.com has no CNAME records.
Question and response
Question
dig mx2.as2.ciberserver.com. NS
Answer
The response has no answer records.
Authority
as2.ciberserver.com. 777 SOA ns1.ciberserver.com. status.ciberconceito.com. 2017092103 3600 7200 604800 900
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0